Variable length catwalk



April 12, 1966 Filed Oct. 14, 1963 IOA FIG.

R. E. WILSON VARIABLE LENGTH CATWALK 3 Sheets-Sheet 1 INVENTOR.

ROBERT E. WILSON ATTORNEY.

April 12, 1966 R. E. WILSON VARIABLE LENGTH CATWALK Filed Oct 14, 1963 3 Sheets-Sheet 2 INVENTOR. ROBERT E. WILSON ATTORKQ.

- p 1 966 R. E. WILSON 3,245,101

, VARIABLE LENGTH CATWALK Filed Oct 14, 1963 s Sheets-Sheet a co 1 N I u m INVENTOR.

ROBERT E. WILSON ATTORN'EY.

United States Patent 3,245,101 VARIABLE LENGTH CATWALK Robert E. Wilson, Santa Monica, Calif., assignor to the United States of America as represented by the Secretary of the Navy Filed Oct. 14, 1963, Ser. No. 316,192 Claims. (CI. 14-18) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon'or therefor,

This invention relates to improvements in catwalks for bridging between a pair of moored surface vessels.

Incertain operations performed by morred surface vessels at sea it is desirable that their personnel have safe and convenient access between the vessels. Rigid span catwalks have formerly been employed for this purpose. Such type of catwalk is usuallyfixed at one end to one vessel and guided for movement at its other end on the deck of the other vessel. If there is no deck space for the guided end it is apparent that this type of catwalk matically shorten and lengthen as the distance between the vessels varies as a result of wave motion of the sea.

Another object is to provide a variable length catwalk, the walking surface of which will remain level irrespective of pitching or rolling of the vessels, or angular variations in their relative positions, as permitted within thelimits of their mooring lines.

A further object is to provide hand rail life lines above the catwalk which automatically lengthen and shorten with variations in length of the catwalk span.

Still further objects, advantages, and salient features will become more apparent from a consideration of the description to follow, the appended claims and the accompanying drawing, in which:

FIG. 1 is a perspective of the subject of the invention;

FIG. 2 is a perspective of FIG. 1 as viewed in the direction of arrow 2, FIG. 1;

FIG. 3 is a top plan in the direction of arrow 3, FIG. 1;

FIG. 4 is side elevation as viewed from line 44, FIG. 3;

FIG. 5 is an enlarged side elevation of the left side of FIG. 4, portions being shown in section;

FIG. 6 is section taken on line 6-6, and

FIG. 7 is a detail as viewed in the direction of arrow 7, FIG. 5.

Briefly, and first with reference to FIGS. 1 and 2, the subject of the invention comprises a pair of platforms 10, 10A secured, respectively, to moored vessels 12, 12A, between which extends a flexible catwalk 14, one end of which is rigidly secured to platform 10A, the other end of the catenary span being supported by rotatable members 16. The latter end of the catwalk terminates below the surface of the water and is provided with a weight 18 which tensions the span and permits automatic lengthen ing or shortening of it depending upon the distance between the vessels.

Referring now to FIG. 5, platform 10 is formed of two sections 20, 22, section 20 being supported by a base 24 and secured to it by a pivot pin 26 for rotation about Patented Apr. 12, 1966 ice a vertical axis 27. A lubricated thrust pad 28 is secured to section 20 and slides along an arcuate face 30 on base 24. Section 22 is secured to section 20 by a similar pivot pin 32 for rotating about a horizontal axis 33. A like thrust pad 34 is secured to one of the sections for sliding across a flat face on the other. Section 22 is thus gimbal mounted to vessel 12 for movement about intersecting vertical and horizontal axes. Section 22 is provided with a shaft 36, supported by spaced bearings 38, 38, the shaft having the rotatable members 16 secured to the shaft for rotation with it. Members 16 are conventional conveyor type sprockets which engage conventional conveyor chains 40.

Section 20A of platform 10A, rotatable about vertical axis 27A, is of the same construction as section 20, and section 22A is similar to section 22, except that in lieu of the sprockets, ends of the chains are rigidly secured to section 22A. To effect leveling of this end of the catwalk about horizontal axis of rotation 33A, a chain bridle 42 is provided to which, is secured a weight 44. As will nOW be apparent, both platforms may rotate about .yertical axes and both ends of thecatwalk span may be rotated about horizontal axes by pendulous masses to thus maintain the catwalk span ends in level position irrespective of pitching of the vessels.

Each platform is provided with a plurality of spaced posts or stanchions 46, hand rails 48, braces 50, and

stairs or ladder 51. The outer pair of posts on each platform support sheaves 52 through which extend cables 54, one above the other, and in the vertical planes of the catwalk side edges, providing hand rails or life lines which may be grasped by personnel walking across the catwalk span. One end of each cable is fixed to a post 56A on vessel 12A, then passes around a sheave 52A, thence through a sheave 52 on vessel 12, thence through a sheave 53,-supported by a post 56 and terminating at a weight 58. The pair of cables along each side of the catwalk may be secured to the same weight if desired.

The walking surface of the catwalk, as best shown in FIG. 6, comprises a plurality of channel shaped steel treads or cleats 58, the ends of which are bolted to flanges 69 on the conveyor chain links. A plurality of apertures are preferably punched in the treads to form rough projections 62 which may be engaged by the shoes of personnel to prevent slipping on the catwalk which will usually be wet. The outer edges of each tread are provided with bent upturned flanges 64 to form safety stops for the feet of personnel in event slipping occurs.

As previously set forth, section 22 is gimbal mounted to vessel 12 for movement about intersecting vertical and horizontal axes 27, 33. Considering span S of the catwalk as a reference plane, such plane may move relative to a third axis 66 extending through the pivoted links of the chains at a point adjacent their connections with vessel 12, this axis being horizontal and perpendicular to axis 33. Thus, while section 22 is gimbal mounted for movement about two perpendicular axes, the span is universally mounted for movement about three perpendicular axes and is thus universally connected to vessel 12. As will be apparent, its other end is connected to vessel 12A in the same manner. Movement of the span about the third axis, just described, adjacent each of its ends, occurs when the vessels are moving vertically out of phase due to wave motion and prevent applications of torque forces to the span about axes 66, 66. Relative longitudinal movement of the vessels permits the ends of the span to move about axes 27, 27A and since the chains engage sprockets 16, 16, afiixed to the same shaft, the chains are equally tensioned by weight 18, this tension of the chains being the only force to which they are subjected as a result of any relative movement of the vessels.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A variable length and self leveling pedestrian walkway for bridging between first and second moored surface vessels, comprising;

(a) a first terminal platform disposed on the deck of the first vessel and mounted for rotation about a vertical axis,

(b) said first terminal platform having a first leveling section extending outwardly beyond a side edge of the first vessel and secured to the terminal platform for rotation about a horizontal axis,

(c) a flexible walkway having one end secured to the first leveling section, V

(d) a weight secured to and depending from said first leveling section adapted to maintain said one end of the walkway level irrespective of pitching of the first vessel,

(e) a like second terminal platform disposed on the deck of the second vessel having a second like leveling section extending outwardly beyond aside edge of the second vessel, the second platform also being rotatable about a vertical axis and its leveling section also being rotatable about a horiz ontal axis,

(f) said second leveling section having an idler member rotatable about a horizontal axis and over which an intermediate portion of the walkway is trained, forming a walkway span between the leveling sections,

(g) the remaining portion of the walkway extending downwardly from the idler member into the water, and

(h) a weight secured to the lower end of said remaining portion for maintaining the other end of the walkway level irrespective of pitching of the second vessel and for tensioning the walkway span.

2. A catwalk in accordance with claim 1 wherein said flexible member comprises (i) a pair of spaced parallel chains connected by parallel spaced transverse cleats forming a walking surface,

(j) said idler member comprising a pair of spaced sprockets non-rotatably connected to a rotatable shaft and around which the chains are trained.

3. A walkway in accordance with claim 2 including at least one cable life line extending between the vessels above one side of the walkway span, said cable having one end fixed to one vessel and trained through sheaves carried by the other vessel, its other end extending into the water, and a weight secured to said other end for tensioning the cable.

4. Apparatus in accordance with claim 3 including a like life line extending between the vessels above the other side edge of the catwalk span and like sheaves and a weight for tensioning same, said transverse cleats having upturned edges forming stops for the feet of personnel walking across the span.

5. A variable length and self leveling pedestrian walkway for bridging between a pair of moored surface vessels, comprising; 7

(a) a pair of spaced parallel chains having a plurality of parallelhoriz'ontal pivotal axes, V

(b) a plurality of transverse cleats afiixed to the chains forming a walkway span,

(0) a first universal joint having three perpendicular axes of movement, one axis being formed by the chain links, securing one endof the span to one of the vessels,

(d) a like universal joint securing the other end of the span to the other vessel, 7

(e) a connection between one end of the span and one vessel for permitting the span to lengthen and shorten, and

(f) a weight secured to the last named end for tensioning the span and permitting it to lengthen and shorten.

No references cited.

JACOB L. NACKENOFF, Primary Examiner.

N. C. BYERS', Assistant Examiner, 

1. A VARIABLE LENGTH AND SELF LEVELING PEDESTRIAN WALKWAY FOR BRIDGING BETWEEN FIRST AND SECOND MOORED SURFACE VESSELS COMPRISING; (A) A FIRST TERMINAL PLATFORM DISPOSED ON THE DECK OF THE FIRST VESSEL AND MOUNTED FOR ROTATION ABOUT A VERTICAL AXIS, (B) SAID FIRST TERMINAL PLATFORM HAVING A FIRST LEVELING SECTION EXTENDING OUTWARDLY BEYOND A SIDE EDGE OF THE FIRST VESSEL AND SECURED TO THE TERMINAL PLATFORM FOR ROTATION ABOUT A HORIZONTAL AXIS, (C) A FLEXIBLE WALKWAY HAVING ONE END SECURED TO THE FIRST LEVELING SECTION, (D) A WEIGHT SECURED TO AND DEPENDING FROM SAID FIRST LEVELING SECTION ADAPTED TO MAINTAIN SAID ONE END OF THE WALKWAY LEVEL IRRESPECTIVE OF PITCHING OF THE FIRST VESSEL, (E) A LIKE SECOND TERMINAL PLATFORM DISPOSED ON THE DECK OF THE SECOND VESSEL HAVING A SECOND LIKE LEVELING SECTION EXTENDING OUTWARDLY BEYOND A SIDE EDGE OF THE SECOND VESSEL, THE SECOND PLATFORM ALSO BEING ROTATABLE ABOUT A VERTICAL AXIS AND ITS LEVELING SECTION ALSO BEING ROTATABLE ABOUT A HORIZONTAL AXIS, (F) SAID SECOND LEVELING SECTION HAVING AN IDLER MEMBER ROTATABLE ABOUT A HORIZONTAL AXIS AND OVER WHICH AN INTERMEDIATE PORTION OF THE WALKWAY IS TRAINED, FORMING A WALKWAY SPAN BETWEEN THE LEVELING SECTIONS, (G) THE REMAINING PORTION OF THE WALKWAY EXTENDING DOWNWARDLY FROM THE IDLER MEMBER INTO THE WATER, AND (H) A WEIGHT SECURED TO THE LOWER END OF SAID REMAINING PORTION OF MAINTAINING THE OTHER END OF THE WALKWAY LEVEL IRRESPECTIVE OF PITCHING OF THE SECOND VESSEL AND FOR TENSIONING THE WALKWAY SPAN. 